Satellites have become a key component in modern life. From telephone and TV transmission, weather reports, analysis of ocean currents and ground imaging, satellites are relied upon in many ways. Enjoyed by civilian applications, many satellites also provide military resources which are vital to national peace and security.
In addition to the orbiting operational satellites, there is a large quantity of debris, commonly called space junk, in orbit as well. There are also hostile forces in different geographic locations that may desire to destroy satellites, and recent anti-satellite missile tests have raised serious concern about the vulnerability of satellites and spacecraft in general.
Deployment of an object in space can be a complex issue. Newton's laws of motion teach, among other things, that for every action there is an equal and opposite reaction. In space, where a space vehicle acts to deploy an object from itself, a force applied to launch the object can and often will result in the space vehicle itself also being displaced from its original location.
As the deployed object typically has a much smaller mass then the space vehicle, the opposite reaction upon the space vehicle is somewhat reduced, but with repeated deployments minor displacements may aggregate into an issue of concern.
Two general options present themselves to address this. The first is to deploy an object with a very small force. By minimizing the force, the deployment is of course slow, but the opposite force against the deployment vehicle is further reduced.
Although this is effective to achieve the separation of the deployment object, it is hardly effective as a countermeasure launch system for defense against approaching space junk or an incoming missile where speed to intercept may be at issue. Indeed if high velocity is desired for the deployed object, it is necessary to equip the deployed object with its own means of propulsion. This may well increase the cost and complexity of the deployed object in undesired ways.
The second is to provide yet another equal and opposite force, such as by deploying objects symmetrically. If objects of equal mass are deployed in opposite directions from the space vehicle, the opposite reactionary forces will cancel. As it is rather unlikely that two objects are desired in opposite directions of employment, one object is truly sacrificial, which likely increases costs as well as contributing to the growing field of space junk. Such a system is technically challenging. If the deployments are even slightly out of synchronization, the effect of opposing forces will not properly cancel and indeed opposing sheer forces may be quite damaging to the space vehicle.
As opposed to symmetrically deploying a sacrificial mass, thrusters may also be used to apply an opposite force to maintain the position and stability of the space vehicle. Here again, the operation of the thrusters must be precise so as to not adversely affect the deployment of the object in the intended direction and/or cause sheer stress to the space vehicle.
If it is desired to deploy multiple objects nearly simultaneously, the issue of applying and controlling equal and opposite force becomes even more technically challenging. If it is desired to deploy the multiple objects on different trajectories, the equal and opposite force control becomes even more complex and challenging. The issue of where on the space vehicle the deployment object is may also factor into the equation and problems of stability control, for if the thrusters are located at either end of the space vehicle, but the object is deployed from the middle or any point not directly in line with opposing thrusters, the control of multiple thrusters will be required.
The use of thrusters of course requires the use of a propellant which is expended in the counter force maneuver. Factors such as weight, internal space, dollar cost, and finite supply do impose limitations on how much and how often counter thrust may be used in deployment systems.
When, as suggested above, the deployed object is intended as a counter measure against space debris, an incoming missile, or other object, speed of deployment and velocity upon deployment may be highly critical issues. Although most space vehicles are of course designed to withstand the stress of ground launch, periodic sheer stresses can be more difficult to anticipate and control. Complex systems to maintain center of mass for the deploying space vehicle and overall vehicle stability introduce greater overall system complexity and at least increase the number of possible points of failure.
Moreover, despite various prior art attempts, space based deployment systems and methods currently do not offer effective options for high velocity deployment, let alone a simplistic system and method for same. Hence, there is a need for a space object deployment system that overcomes one or more of the issues and problems identified above.